Track One: Modeling Coupled Inland-Coastal Systems for Stormwater Management


Principle Investigators: Craig Colton, Scott Hagan, Clint Willson

There is a need to create coupled coastal-inland ecological models that portray an accurate assessment of current and future risk. Flood inundation maps (FIMs) are an effective way to communicate flood risk – unfortunately, the public’s access to these maps is limited. In addition, maps that are available are typically developed for a limited set of conditions (i.e., return intervals or design storms) and have major simplifications (e.g., 1-D steady). To accomplish objectives laid out in this proposal, it is crucial to both quantitatively and qualitatively assess past, present, and future conditions of landscape suitability for development.

The team proposes two parts to the modeling of coupled coastal-inland systems:

  1. An Amite River watershed/basin (ARB)-wide model, with sufficient resolution and interaction with community/local scales and integration with dynamic downstream boundary conditions and forcings; and
  2. Continuous collaboration and engagement with the well-being, design and policy groups as well as local ecological knowledge holders, to inform modeling efforts and impart local knowledge into model design and development of the decision support (interface) tool.

While there has been some hydrologic and hydraulic (H&H) modeling work done for the Amite River basin, the models have been one-dimensional, utilized mostly for the FEMA Flood Insurance Program Studies or for localized drainage planning or design or to predict river stage hydrographs.  In addition, none of these models have been designed to produce flood inundation maps, are capable of being useful for basin-wide floodplain management or planning, emergency response, or are able to consider the impact of downstream boundary stressors.

This project proposes building an unsteady coupled one- and two-dimensional H&H model of the ARB that is capable of:

  1. Incorporating detailed measured or projected spatial and temporal rainfall runoff forcings;
  2. Capturing the complex topography of the rivers and bayous as well as the flood plains, thus more capable of simulating the flow patterns within the rivers and bayous as well as the flood plain(s);
  3. Integrating downstream boundary conditions (e.g., higher tailwater, pumping stations) and potential future impacts of coastal land loss; and
  4. Producing flood inundation maps.

The data collection efforts, model framework, and model & decision support tool development will be based on:

  1. Models and programs that have been developed for similar purposes (e.g., Gilles et al., (2012), Chen et al. (2014), Bhatt et al., (2016)  Doong et al. (2016), Hovenga et al. (2016);
  2. An exhaustive review of flood centers (e.g., Iowa Flood Center, Rice University SSPEED); and
  3. Collaborations with the NOAA National Water Center- and CUAHSI-sponsored Summer Institute, where two of the Summer 2016 themes are hyper-resolution hydrologic modeling and flood inundation mapping.

In addition, the team will also have multiple meetings with local subject matter experts (e.g., drainage officials and engineers) to identify key drainage-related natural and anthropogenic features and have team members with coastal process expertise (Hagen) perform detailed analysis of parameterizing and incorporating landloss projections and storm-related processes into the basin-wide H&H model.

The basin-wide model and FIMs will be calibrated and validated for a variety of historic storm events, ranging from 5-10 year “design” events to the 2016 event. This model will then be used and/or extended to:

  1. Simulate a variety of historic and climate model-projected meteorological events as well as future sea level rise and land loss projections;
  2. Develop probability maps of flood inundations under current and future conditions;
  3. Incorporate local/nested models that go down to the community/neighborhood scale;
  4. Test the effectiveness and impact, at the local- and basin-scale, of mitigation and planning strategies developed by the Well-Being, Design and Policy groups; and
  5. Be linked to a decision support (interface) tool for planners and designers, decision-makers, and elected officials.